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What is more environmentally friendly? An A320 or a car?
Presuming the A320 is at least 80% full (of passengers) and comparing it to a typical road car with 2 people inside, which one is more environmentally friendly, per passenger mile?
I have attempted to do some rudimentary calculations, but then was reading that because aircraft release their emissions at altitude, this offsets (?) some of the environmental impact.

Define environmentally friendly. Are you referring to global warming or air quality (e.g. fine particulates)?

(also, the typical road car has one person inside, sadly)

This probably depends on the distance. I cannot believe that flying 50 km or about with an airliner could be more environmentally friendly.

"More environmentally friendly" or "less environmentally damaging"?

I think the scope and definition of this question needs to be nailed down a lot better - at the moment it's impossible to give a decent factual answer to it (and good, factual answers are what the stack exchange network is all about)

@CaiusJard Feel free to edit the question

None of them are environmentally friendly. Also, you probably wouldn't drive from NYC to Vegas for a week-end. Flying will have a much larger impact simply because it makes it possible to burn a lot of fuel in a short amount of time and for a small amount of money.

A fair comparison would also put the car at 80% capacity.

@TREE That depends. One or two people is a much more typical use case for a car than it is for an A320. On the flip side, it turns out that 80% is actually a bit on the low side for airlines. The worldwide average load factor is about 82% and it's about 86% in the U.S. If you're comparing the impact of a couple taking a trip, then the impact of 2 people in a car vs. an airplane with 80+% load factor is a perfectly fair comparison.

To add another point to consider you should think about the environmental impact of the creation of the plane and the car too.  I was confronted with 'a study' purporting to prove that a hummer was better for the environment than a bicycle before.  When I dug in to it there was a number of dubious assumptions.  A very long average lifespan for the car and a very short average lifespan for the bike (this makes the impact of the manufacture of the bike bad).  That you would have a car anyway so any time you cycled instead of drove you were making the car less efficient (this one was fallacious).

Also, the 'fuel' for the bike was assumed to be very expensive (eg: the cyclist was eating a steak every time the took the bike out) but the assumption that cyclists eat more (let alone more of the most environmentally damaging food) than motorists was unfounded.  If you wanted to make the case that a plane is better for the environment than a car you could consider picking and choosing some of those ideas.

Are you going down the road to the chemist's, or are you crossing an ocean and a few tectonic plate boundaries?

I think you should be comparing the car to private air transport and the long haul bus to narrow body aircraft like the A320. The figures will then look completely different. A Scania touring does roughly 18L/100km with about 50 pax. An airplane sees a higher average loadfactor than a bus but even at 50% LF it beats the A320..

do you take into account all airport related operations (involve vehicles), and the transport to the airport? and vehicle cycle of life (construction, recycling,....)?

How about flying from New York City to Los Angeles with an 80% full A320, vs making the trips with cars to take the same number of pax the same distance? Or buses?

Overall, the two very different methods of transportation have surprisingly similar amounts of emissions, so close it's tempting to oversimplify things to a statement like "planes are 20% more efficient than cars". The exact circumstances make it so you can't say one is better in many or even most circumstances. Even worse, different definitions of "environmentally friendly" can produce estimates that vary by 50 to 100%.  At the end of the day, for a two-person medium-range trip, a plane is slightly better for greenhouse gas emissions.
Expert Sources
The general question here about cars vs planes has been studied in great depth by experts, so I'll refer to them wherever I can. It's also a tricky matter where slightly different assumptions can lead to noticeably different outcomes. For example, BBC published a great article on the subject3 based on the UK's BEIS reports. The EPA also published a detailed report1 on vehicle efficiency that's regularly updated.  I've reformatted a table from that report here and made the assumption that only two passengers are in the automobile.

The UK's Department for Business, Energy, and Industrial Strategy's 2019 GHG Conversion Factors for Company Reporting reports similar numbers but with a different methodology.  These numbers do not include other emissions like contrails and soot, which can be according to the BEIS can be accounted for with a 1.9x multiplier for aviation.
Your question asked specifically about an A320. According to the the BEIS's report, an A320 is about average in load factors and emissions except for (rare) long-haul.  So if you chose an A320 and not an A380, your long-haul numbers would be even better than suggested by the table above.
If, And's, and But's
There are lots of considerations here, like vehicle fuel efficiency, extra hotel visits, cargo, etc.  However, we could just be getting nitpicky, so let's look at how big a factor those are.  For example:

If you're in a car, your typical trip along some of the busiest airplane routes is about 1.08 to 1.27 times longer than a trip directly point-to-point (my own estimates)
An extra 50 lb. suitcase would require about 33 g CO2 per mile 1
An extra passenger in an automobile adds minimal extra emissions, but a lot of extra emissions on a plane
Cars produce several times more CH4 per passenger mile than airplanes do, and a little more N2O.  But by my estimates this makes a small difference of less than 1%
Car emissions can vary a lot, with a 1984 SUV producing 8 times as much CH4 and 20 times as much N2O compared to a recent sedan.1.
Getting to and from the airport might take an extra 20-60 miles of travel each way
Staying in a hotel room (you're not really going to drive from San Diego to Portland in one day, right?) creates an extra 15.13 kg CO2 2

If we graph these considerations together we can compare their size. These are rough estimates and your exact emissions will vary.

Some of these considerations are huge, although some other considerations like staying in a hotel room or the trip to and from the airport are pretty minor.  It makes little sense to say air travel is better for the environment without adding that many automobile trips are, in fact, better because there are 3+ people traveling or the trip is short.
It's an apples to oranges comparison
However, just comparing emissions per mile between the two is misleading. There are some big considerations like:

Automotive traffic contributes to smog
Many people go places by plane they would never go to by car
Air travel often means you can't travel as freely at your destination
When traveling by air you may have to drive something other than your favorite Tesla or Hummer at the destination

Contrails', soot, NOx, and other non-greenhouse-gas emissions effect on climate makes for a similar apples-to-oranges comparison.  Contrails cause enough heating for their effect alone on global temperatures to be measurable.  However, contrails also go away after just about a day, while CO2 emissions stay around for decades, some of it taking several millennia to dissipate. High altitude NOx similarly becomes less potent much faster than CO2.
Despite all these caveats, you can try to account for such emissions with something simple like BEIS's 1.9x multiplier, which the UK's BEIS says is often necessary, but admits that "there is no suitable climate metric to express the relationship between emissions and climate warming effects from aviation, but this is an active area of research. Nonetheless, it is clear that aviation imposes other effects on the climate which are greater than that implied from simply considering its CO2 emissions alone."

Sources:
1. "Emission Factors for Greenhouse Gas Inventories", EPA, last updated 9 March 2018
2. CHP in the Hotel and Casino
Market Sectors, EPA
3. Climate change: Should you fly, drive, or take the train?, 24 August 2019, Reality Check column
4. UK's Department for Business, Energy, and Industrial Strategy's 2019 GHG Conversion Factors for Company Reporting

Does that include take-off? because lifting a car to the top of mount everest in the space of 10 minutes would use rather a lot of gas!!! sure, cruising afterwards is about the same, there's a lt of figure twisting going into official sources, i'm after the total including lift off.

@com.prehensible This does include takeoff.  That's the biggest reason why short flights are much less efficient than long flights- a two hour flight can't spend much time at an optimal cruising altitude.

There is other research by UK Govt/Defra which contradicts the EPA by about 50% including hte NOx emissions, it states that aeroplanes account for 195g to 254g CO2 equivalent, compared a 2 passenger car at 85g CO2 equivalent. Someone has got it wrong by 80%, Either the UK Govt or the EPA or both. You have relayed some disinformation from one source or the other based on "High Altitude NOx effects". Is the EPA reliable? https://i.sstatic.net/IHrrO.png

This is a complicated matter and the discrepancy you're noticing appears to be in the methodology.  I see no evidence anyone is deliberately spreading "disinformation".  The "80%" difference you note is largely from the 1.9x multiplier for non-GHG high altitude emissions like contrails, which I already mentioned. The 2019 BEIS report notes that this 1.9 multiplier is often important, but it's optional, "not a straight forward instrument", and "subject to significant uncertainty". Thanks for pointing me to the BBC article I've updated my answer to try to address your concerns.

Cheers! there was something fishy about that. The EPA related image is mis-transcribed and wrong by 10 orders of magnitude, see accepted answer: https://earthscience.stackexchange.com/questions/19577/usa-and-uk-government-report-on-plane-emissions-200-difference-which-is-rig/19582#19582

I'm going to simplify and assume that jets and cars burn the same fuel, and output the same exhaust, CO2, NOx and all. I'm going to compare only short-haul flights against cars.
According to Wikipedia, an A-320-NEO does 1.95L/100km per seat. Assuming flying at 80% capacity, that gives us 2.4L/100km per seat. According to
The Car Guide, a 2019 Honda Civic does 6.5L/100km. Assuming an average car carries 2 people, that gets 3.2L/100km. It would seem like flying is slightly better, using this simplistic measure.
Keep in mind that the longer you fly, the better the mileage, since the takeoff and climb are the fuel guzzling segments.

Comments are not for extended discussion; this conversation has been moved to chat.

This simplification is so great that I believe it ends up being inaccurate. Not only do they not burn the same fuel and output the same exhaust, but they release exhaust at different altitudes. Fine particulates don't really matter miles in the air, whereas water vapor does. In an urban city, it's the exact opposite.

It depends on what you mean by "environmentally friendly." Just for an example, let's consider a 1000 mile trip.
An A320 burns about 5 gallons of fuel per seat per hour, and with 150 seats this comes to 750 gallons per hour. A 1000 mile flight will take about 2.5 hours, so this comes to 12.5 gallons per seat, or 1875 gallons total. This means that 2 seats worth of fuel would be about 25 gallons total.
For driving, if you assume a fairly efficient car will get 50 miles per gallon, and the drive is not as direct and is 1300 miles, this comes out to 26 gallons total.
So, on the face of it, they are approximately equivalent in fuel usage.
However, if the flight is only 80% full, then if you choose not to take the flight, it's still going to happen. This means the difference in fuel usage will be from the reduction in weight of two people and their luggage. The fuel usage will decrease by about the same amount as the weight reduction compared to the total aircraft weight. If you approximate 2 passengers plus luggage at 400 lb, and aircraft weight at 140,000 lb, based on the 1875 gallon fuel consumption from before, the additional fuel burned by the two people choosing to fly is about 3 gallons total. This makes it much better than driving.
But not all emissions are equal. The aircraft emits most of the exhaust higher in the atmosphere, where it will create contrails that help trap solar energy.

There's a bias in your calculation. 50 mpg means they're driving the most efficient ICE cars in the US tipping the calculation in favor of cars. Whereas US average for a new 2017 model is 25 mpg, almost 30 if you leave out small trucks. Using a more realistic, but still high, 30 mpg gives 43 gallons for the car trip or 21.5 per seat; a rather different result. The calculations might be different elsewhere in the world.

@Schwern: The most efficient ICE cars in the US get quite a bit better than 50 mpg.  My Honda Insight has averaged over 70 mph for the 16 years/150K miles that I've owned it.  Though of course you can find plenty of vehicles that get much worse mpg :-(

@Schwern, nothing in the question restricts the answer to the US. In Europe where the average car size is typically much smaller the average MPG are much higher ... I do 60mpg without breaking a sweat on a mix cycle with my little car (skoda 1.4d). And some cars do even better ...

This stuff makes it sound like the canard "flights kill the environment" is a bit too simplistic. If you're going to travel, it isn't clearly much more/less green to take a car versus a plane. If flights are "less green", it's more because they let you rack up a lot more distance a lot faster . It's the total miles/kilometers traveled in a span of time, say a year (~32 megaseconds), not the method, that really counts for more than the per-distance efficiency in these cases.

US/Europe fuel consumption figures are also confused because it isn't clear what is meant by "mpg".  Do you mean a proper 10-fluid-pounds gallon, or the short-weight American gallon?  (The same car driven through the same test cycle will get 40mpg in America, and 50mpg in the UK.)

Which of the great Imperial unit countries uses this 10-pound gallon? Myanmar, Liberia, or USA? noting that fuel in the UK is sold in litres...

@reirab the comment before

@Harper Ah, sorry, somehow I missed that entirely. I honestly didn't realize the "fluid pound" was a thing (though I'm familiar with fluid ounces.)

@Harper fuel in the UK is sold in liters, but car fuel economy in the UK is measured in miles per (imperial) gallon.

While not specific to an A320, nor a make/model of automobile, these averages may help put your question into perspective.  How any of it relates to "environmentally friendly" is purely subjective.
"...the average fuel consumption in 2017 was 34 pax-km per L (2.94 L/100 km [80 mpg‑US] per passenger)..."
from https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Flight_distance
"...The average fuel economy for new 2017 model year cars, light trucks and SUVs in the United States was 24.9 mpgUS (9.4 L/100 km)..."
from https://en.wikipedia.org/wiki/Fuel_economy_in_automobiles
Note the airliner value is per passenger, the automobile is per vehicle.  if you put 4 people into the car it will 4x the passenger miles, which in this example is 99.6 (if the car has 4 passengers)
For pure fuel efficiency, the automobile, on average, would be more efficient, if both travel at the airline average of 80% passenger capacity.
This sadly isn't reality, there are too many factors left unaccounted for...the cargo transported with each flight that an automobile cannot carry.  the fact that flying can go places you cannot drive, and therefore the plane is infinitely more fuel efficient.
 the fact that automobiles probably do not average 4 passengers, but the airline calculation was based on actual passenger and fuel consumption values.  there is no mention of the emissions associated with the different types of fuel (jet vs 87 octane).  there is no mention of the environmental impact of building and maintaining an airport, or building and maintaining x miles of road.  etc etc etc

Welcome to the site.

Note: the UK Govt report gives figure that is 150-200% higher than the USA's EPA agency, stating that it's "High Altitude Effects" of CO2... So, either one or the other report is wrong by 100-200 percent!
Here is another study which is at odds with the previous figures, because it includes high altitude effects, where emissions are released at 8km altitude versus close to sea level... Nitrous Oxide is 300 times more potent than CO2 as a greenhouse gas, and it falls to the ground easier from road level, it's 1.5 times denser than air. NO2 emissions released at 8km altitude are significant greenhouse agents.

Source: bbc.com

"Note: Car refers to average diesel car". Here in the US, there's nothing "average" about a diesel powered car. Hybrids are far more common than diesels (Source: personal observation). This is sourced from the BBC and I realize that diesels are far more common in the UK and EU than they are in the US. I thought I would point out that this may have a different impact based on where in the world you are.

Hey, indeed. Petrol is about 5-10 percent less CO2 than diesel, although they are fairly similar. I want a hybrid here as well, send one over.

@FreeMan, Here's another difference from the USA and the UK Govt greenouse effect maths system... The UK report states that aeroplanes are about 250% to 320% more polluting than a car with 2 people car. due to the high altitude effects of CO2... If the EPA forgot the high altitude effects, that makes the most upvoted answer on this page factually wrong by about 250%?!?

I convinced my friends not to fly to Croatia from Germany for our holidays and make a road trip instead for climate reasons. I calculated the climate footprint beforehand and results were a lot different from the ones presented here. Reading this, I became  unsure whether I my recommendation was right, So I asked some scientists about the above calculations. One of them is Dr. Bernhard Stoevesandt, the Head of Departement
Aerodynamics, CFD and stochastic Dynamics at Fraunhofer Institute for Wind Energy Systems IWES. That is the most renown institute in Germany on that subject.  This is the translation of what they said:

The climate impact of air trafﬁc is to a large degree caused by changes in cirrus cloudiness resulting from the formation of contrails. Following the guidelines of the german environmental ministery the climate impact of airplanes is to be estimated around three times the impact of the actual CO² emissions of the plane due to the formation of contrails. For details, here is the recent research paper inclunding a summary of relevant studies: https://www.atmos-chem-phys.net/19/8163/2019/acp-19-8163-2019.pdf

I guess, the above calculations have to be adapted accordingly.

Added to the contrails is the existence of NO2 from aeroplanes, it's 300 times more potent greenhouse gas than CO2, as are other heavy organic emissions, like heavy smog from the city, at 8km altitude they can take months to fall from the air.

Depends.
Are you bringing stuff?
The problem is that the A320 quickly becomes prohibitive, or even impossible, if you are transferring

too much stuff for common luggage, or, too much stuff to drag from claim to car rental
balky outsize stuff that won't handle as baggage
fragile stuff that won't survive as baggage
Hazmat or prohibited stuff that shouldn't fly
Valuable stuff that's a high theft risk

For instance you can't purge chainsaw gas enough to make it flying safe, and the long lumberman-tier bar will be too fragile and balky. The chest of Snap-On tools will go home with a baggage handler.  Also, Hertz will not want that in their rental car.
The other factor is the weight of substantial stuff adds proportionately to the A320's fuel burn (i.e. an A320 with 1% more gross weight burns 1% more fuel) -- but it does not do so to an automobile at cruise.  the automobile has slightly higher rolling resistance, zero acceleration energy since it's at cruise, and zero effect on aerodynamic drag. The last one dominates fuel consumption at freeway cruise.  And that's my direct experience talking; I've driven my car long distances both empty and laden in comparable conditions.
Will you be extensively using a car at the other end?
In this case, you may be better off bringing your efficient car, rather than renting whatever run-of-rental-shop they happen to hand you.  In my experience, most of the time, the efficient cars are gone, and they cheerfully "upgrade" you to a bigger car with abysmal fuel economy.  I have often sat in the waiting room waiting for the efficient car I asked for to be cleaned and prepped, because I would be putting a lot of miles on it.
Early this decade, they were charging a significant premium for boldly-efficient cars like the Toyota Prius.

All good points. Bulky, excess, or valuable stuff could also be shipped separately, where the incremental environmental cost is still pretty low.

Aircraft fuel consumption is also quite dependent on the actual distance traveled - while in cruise the engines are quite efficient, this is quite different when climbing - where they are operated near their maximum thrust. So long haul flight might get a slight advantage over a car - but on short hops, a placne can consume significantly more fuel than a car...

I think most airlines climb at 80% thrust

Middle-haul  flights are the most efficient.

The answer is that it is dramatically more environmentally friendly in terms of CO2-equivalent greenhouse gas release to drive any given distance than to fly it. The average American drives three times the distance from San Diego to London, yet the relative contribution of that year of driving versus a single flight from America to London is less than 150% more (just eyeballing the difference in the plot in the link below).
And as others have pointed out, aircraft burn through fuel at a precipitous rate during take-off and landing, so for shorter distances this disparity is likely to be even greater as the total ratio of cruise altitude efficiency becomes lower.
The dramatic impact that aircraft contrails have on this matter really can't be overstated.
Comparison of air versus road travel: https://phys.org/news/2017-07-effective-individual-tackle-climate-discussed.html
Average distance driving: https://www.fhwa.dot.gov/ohim/onh00/bar8.htm

Neither link makes any data driven comparison between air travel and car driving. The links do not confirm your statements.

That is not true. Link one establishes a comparison between a single flight and a year's worth of driving. I use the second link to get an estimate of how many miles one drives in a year. The average is ~15K/year and the distance between London and San Diego (among the longest of flight options between the two continents of sizable traffic. If the two forms of travel were equivalent mile-for-mile, then the savings of not driving for a year in link 1 would be roughly three times the size of not flying to europe once, which it certainly is not. Very generous approximations were made.

Also, if you want more details on Link one, you are encouraged to follow the link provided's link to the Environmental Research Letters academic article in which the findings are initially reported. However, because there are often restrictions on access to academic journals, it is common practice to use these second-party summaries of original scientific work when interacting with the general public.


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Do any companies offer 'ejection' experiences?
Most airlines now offer fear of flying courses, most airports provide flying lessons and some specialist companies offer zero-gravity flight experiences.
Are there any companies that provide 'ejection' experiences, where you can fly an aircraft and eject from it at a pre-determined location?
Please note, I'm not talking about sky-diving. I want to actually use an ejection seat.

No, there are no companies offering ejection seat experiences, for many reasons:

Cost: Ejection seats are expensive, base costs are somewhere around $100,000 per seat. Seats can't generally be re-used, therefore the cost of an experience is going to be well over that
No platform: There are airplanes that are designed to eject someone and keep flying safely, they are used exclusively for seat testing and not open to the public. Someone would have to develop and build an airplane designed to give a "fighter plane ejection" experience
Ejection is incredibly dangerous: the chances of injury or death are very high. Ejection seat companies have used test dummies instead of humans for decades for this reason
Ejection can lead to life changing health issues: the G forces on a modern seat are at least 12G, and go up from there - they can't be any less or you won't clear the airplane. This compresses the spine and can lead to debilitating, life lasting injury. If your ejection position isn't right you can break or lose a limb
Ejection isn't fun: there's not a pilot or crew member in existence who has used an ejection seat and said "Whoopee! Let's do that again!" Instead they say, if they are capable of speech, "Ow!" or "Please get me clean underwear."

So a company would have to spend tens of millions to develop a system that only rich people would be able to use, still less would want to, and a very precious few would be crazy enough to try.

I agree 100%, and upvoted this answer.  Not hard to imagine though, a very similar response 100 years ago to someone asking about parachuting for fun, but look at the industry now!  And while it is a very bad idea to intentionally experience a 0/0 military seat for recreation, it’s also not hard to imagine some enterprising company in the future designing a much milder, less expensive and reusable recreational seat to replicate the experience on a roughly 25% scale.

Heck, I might even consider punching out of a specially configured 208 Caravan at 80-100KIAS and riding a 3-4 G rocket seat upwards for a few hundred feet.  3-4 Gs is very fun!  I’m not saying such a company would get a solid return on their investment, but we do know that people would be willing to try it...

I'm not sure that's what sunk cost means..

A sunk cost is one that cannot be recovered @Antzi, I'm happy to rephrase though.

"There are no airplanes that are designed to eject someone and keep flying safely" - not quite true, there is one: Martin Baker maintains a Meteor for exactly that purpose http://martin-baker.com/2018/06/18/martin-baker-meteor-back-action/

Cool @PartyArk, I thought they'd retired that.

@GdD sorry you are 100% right

Minor nitpick: I believe the F-14 can eject only the RIO and keep flying. Whether that was a design requirement or just happened to work out that way, I don't know, but we have at least anecdotal proof of it being the case. The airframe is also still in service with the IRIAF.

Also, shameless plug of a question about ejection fatality rates: https://aviation.stackexchange.com/questions/68529/what-are-the-ejection-injury-and-fatality-rates

There's more than one 2 seater which has been known to keep flying after the RIO ejects @AEheresupportsMonica, the F4 is another that comes to mind. They aren't designed for that and there's no guarantees it will work though.

Yes, there is.
Since ejecting from an aircraft destroys the aircraft, you'll just have to buy one with an ejection seat. I'd recommend an L-39 or a Dassault Alpha Jet. They can be had for about \$1.5-$4 million.
After that you can pretty much do whatever you want. Head out over the ocean, pull the ejector handle, wait for the Coast Guard.

Seriously though, no. The chances of serious injury or death, especially for somebody who does not have the years physical training required of fighter pilots is almost sure to result in your own permanent injury or death. Ejecting from an aircraft destroys the aircraft, so nobody is offering a "fly and eject" experience package. Might as well take the "Russian Roulette" experience with it, you're chances are probably better with that game.

I don't think ejection always destroys the aircraft. There are stories out there about planes continuing to be flown after crew has ejected. https://www.quora.com/In-a-two-seater-combat-aircraft-if-one-of-the-pilots-ejects-can-the-the-other-pilot-continue-flight-and-land-safely

Apparently the odds of surviving an ejection are around 84% https://aviation.stackexchange.com/questions/68529/what-are-the-ejection-injury-and-fatality-rates

This literally had me laughing out loud in the office... thank you! :)

https://aviation.stackexchange.com/questions/52797/why-does-martin-baker-use-a-gloster-meteor-as-a-testbed-for-ejection-seats

The Cornfield Bomber is another example of a plane that survived ejection. It was even repaired and returned to service!

@Notts90 This is not really a relevant number to this question. One can expect that for a planned ejection, the rate would be closer to 100%.

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How to reduce cosmic radiation in commercial aviation?
There have been some (somewhat limited) studies that show (certain) cancer risks increase with flying hours:

The risk for all cancers, malignant melanoma, prostate cancer, basal cell carcinoma of skin, and basal cell carcinoma of trunk increased with an increase in number of employment years, cumulative air hours, total cumulative radiation dose, and cumulative radiation dose sustained up to age of 40 years.

Is there anything that can be modified within aircraft design to mitigate or lower this risk? (to either both passengers and pilots, or at least just the pilots (but what about cabin crew).
An (admittedly terrible) example might be to have some sort of protective layer within the aircraft body, perhaps lead.

I commend your research for things that will potentially kill you as a result of flying.

@DanHulme Not really... that question doesn't mention aircraft design at all.

Not really. The sole way to stop X-radiation and gamma radiation (which are the same thing) from reaching the people inside is to make the aircraft skin far thicker and denser, and thus incredibly heavy.
The only other things you can do is what's already done and has been for decades, which is to reroute flights away from regions where there's intense incoming radiation, which happen to be the far northern and southern areas near the poles specifically, and then especially during periods of high solar activity (and thus intense auroras).
What's also done is limiting crew hours, especially on polar routes, rotating crews between polar routes and routes that run closer to the equator.

Or - and not really practical - fly lower, let the atmosphere block all the nasty stuff like it does for folks on the ground.  And now composite aircraft bodies mean the passengers will be exposed to more as well, whereas before there was at least some aluminum to block a little bit of the cosmic rays ...

@CrossRoads Actually carbon fiber composite blocks radiation better than aluminum or titanium.

@TomMcW mostly because it can be thicker for the same mass...

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Why didn’t the Concorde have flap-canards like the Tu-144?
One of only two ways of which I am aware in which the Tu-144 was “ahead” of the Concorde1 was in its use of retractable flap-canards, which increased the lift on the front of the aircraft at low speeds, thus allowing the aircraft’s elevons to be used as flaperons (flapevons?) for increased lift without pitching the nose down uncontrollably, and, thereby, decreasing the required takeoff and landing speeds;2 the Concorde, in contrast, had no high-lift devices at all as produced.3
Although the Concorde’s myriad aerodynamic advantages over the Tu-144 allowed it to take off and land at much lower speeds than the Soviet SST even without any canards, its takeoff and landing speeds (especially the former) were still very high by airliner standards, with a typical approach and landing speed of 160 kts (296 kph; 184 mph), and a rotation speed, at maximum takeoff weight, of nearly 200 kts (370 kph; 230 mph).  This made the Concorde require very long runways to take off and land (and required the readdition of afterburners in order to keep its runway-length requirements from being even longer), forced the development of a whole new type of brakes in order to be able to stop the aircraft during a landing or rejected takeoff,4 and greatly increased (due to a] centrifugal force, and b] downforce on the main-gear tyres during rotation) the stress on the tyres, and the potential (and actual) destructiveness of a tyre failure.
Why didn’t the Concorde use flap-canards to further decrease its takeoff and landing speeds?

1: The other being the use, in later Tu-144s, of a non-afterburning turbojet.
2: Despite this, the Tu-144 still had a much higher landing speed than the Concorde, thanx to all its other aerodynamic deficiencies.
3: An improved version (the Concorde B) was planned, which would have included leading-edge droops (as well as larger wings and non-afterburning engines) for improved efficiency in subsonic flight and decreased takeoff and landing speeds, but the Concorde programme was cancelled just as the production line was getting ready to build the first Concorde B.
4: Not that I’m complaining about carbon brakes!

"thus allowing the aircraft’s elevons to be used as flaperons". I wonder if this is actually true. Neither actually has a good enough FBW to enable a full canard. On Tu-144 it's more like a vertex generator than a control surface.

Is there really that much downforce on the gear at rotation? The plane's about to take off so shouldn't lift be almost equal to weight, leading to very little downforce on the gear, right?

It did not need them. Concorde could operate from most commercial airports and did not need especially long runways. Retractable canards add drag and the mechanism is a point of failure.
I fail to see how Tu-144 canards is a “superior” feature as they were added to support a less effective wing.
Very much related: Why is the Tu-144 the only commercial airplane with canard configuration?

Yup, the fewer moving parts the better.


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Why doesn't the Convair 580 have check valves to prevent inadvertent fuel transfer?
The Convair 580's fuel system is composed of two wing-mounted fuel tanks (one in each wing), each with its own shutoff valve (which can be closed to isolate its respective tank from the rest of the fuel system and prevent fuel from entering or leaving the tank) and boost pump (which forces the fuel, under pressure, to the respective engine(s)), plus a pair of crossfeed valves (one on each side of the aircraft) to allow an engine to be fed from its contralateral fuel tank if necessary.
Normally, the crossfeed valves are kept closed, and each engine is fed from its ipsilateral fuel tank.  However, if crossfeeding does become necessary (for instance, if one fuel tank drains due to a leak [in which case both engines must be fed from the non-leaking tank] or if one engine fails [in which case the remaining engine must be periodically switched between the left and right tanks to prevent the weight of the fuel in the tank ipsilateral to the failed engine from unbalancing the aircraft and causing a loss of control]), the crossfeed valves are opened, and the tank shutoff valve for the tank not being used must be shut off; otherwise, the boost pump for the tank being used can end up pumping fuel into the tank not being used rather than to the engines.1
Transferring fuel from one tank to the other is expressly prohibited for the Convair 580, as doing so could lead to, in increasing order of severity:

Fuel being lost through the overflow vents in the recipient tank (which is bad because it wastes fuel);
The aircraft's entire fuel supply being pumped into the tank not being used (which is bad because it can result in both engines flaming out despite the aircraft's fuel system containing plenty of fuel);
The recipient tank (and its associated wing) bursting (which is bad for reasons that should be immediately obvious).

However, there is no mechanism to prevent fuel from transferring between tanks if the pilot forgets to close the shutoff valve for the tank not being used, which leads to the Convair 580 being an aircraft where fuel transfer is, simultaneously,

Prohibited under any and all circumstances, as doing so could cause a fuel tank to overflow and/or burst; and
Quite easy to make happen, simply by opening the crossfeed valves and forgetting to close the shutoff valve for the tank not being used.

This seems almost trivially easy to solve, by placing one-way check valves in the lines leading from the fuel tanks so that fuel is physically prevented from transferring from one tank to the other, but, according to the NTSB (footnote 46, page 25/35):

One-way check valves are not typically installed on airplanes, and the accident airplane did not have one installed. According to a Kelowna Flightcraft representative, one Convair 580 operator modified its fleet of about 30 Convair 580 airplanes in the 1960s under an engineering order by installing a one-way check valve, which prevented fuel from flowing back into the fuel tanks when the fuel tank shutoff valve was left open. However, the representative stated that this operator was no longer in business and that its airplanes had represented a small percentage of the entire Convair 580 fleet.

I can see no reason not to use one-way check valves in the Convair 580's fuel system, given the potentially-lethal consequences of transferring fuel between tanks and the frightening ease of inadvertently doing so.  So why doesn't it use them?

1: The boost pump for the tank not being used must be shut off to keep fuel from being pumped from that tank, rendering it incapable of preventing fuel from transferring into the tank not being used.2  Even if the pilot forgets to turn it off, fuel can still be forced through the pump in the reverse direction if it (the pump) happens to be less powerful than the boost pump for the tank being used.
2: And, if the pilot closed the shutoff valve without turning off the associated boost pump, the force of the pump pumping against the closed valve could potentially cause a fuel line to burst.

A check valve is another failure point in the fuel system (they can stick) so you have to do a risk analysis to decide if the benefit of adding them outweighs the risk of the added failure mode introduced, with sufficient weight to justify mandating them by AD.  With no AD, it's up to KFC to decide if it wants to do anything on its own.
Assuming this was a one-off event (the report only mentions one previous less serious  but similar event) that is more or less attributable to bad piloting, the balance of risk, when added to the burden of forcing an AD on operators, would have been determined to not fall within the threshold needed to mandate such a change (I've participated in these kinds of projects over the years).
If another crash or two happens later with more or less the same circumstances, it's more likely to trigger an AD.  But these airplanes have been flying a very long time like this.
Yes there is a tendency to think the need to do something is obvious, but if ADs were issued for every potential design deficiency to cover every eventuality, there would be eleventy jillion ADs out there.  That being said, there was probably an internal debate with discussions between Transport Canada and KFC, with pro and con factions arguing it out, and TC was probably convinced that mandating check valves would not provide sufficient risk mitigation to justify the burden of issuing an AD (The FAA could do something on their own, but usually they will work with TC on this and go along with TC's resolution).


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Why do (or did, until very recently) aircraft transponders wait to be interrogated before broadcasting beacon signals?
An aircraft’s transponder transmits signals that announce (at the very least) the aircraft’s identity, altitude, and direction of motion (plus, for most newer aircraft, a whole slew of other useful information); this is what allows secondary surveillance radar (SSR), the backbone of modern air traffic control, to function,1 and what makes it possible for aircraft’s TCAS to see other nearby aircraft and (if necessary) warn their pilots not to collide with them.2
For a long time, I thought that this worked by having the transponders broadcast this information in the blind, in case there was a radar or TCAS within range who might want to know about the aircraft attached to the transponder.  I’ve recently learned, however, that most aircraft transponders “speak only when spoken to”, not transmitting their information until they hear a radar or TCAS shouting “Anyone there?” into the deep blue sky (although ADS-B, which works essentially how I thought all transponders worked, is being rolled out, and will soon become mandatory in the U.S. for many aircraft) - and that this transmission is sent only to the shouter, and not to anybody else who might have an interest in the matter.3
I don’t get why most (or, until very recently, all) transponders don’t broadcast unbidden; it’s obviously feasible (otherwise we wouldn’t be able to have ADS-B), and would eliminate the need for those big, expensive SSR transmitters (ATC would just need a small, cheap receiver, plus a primary surveillance radar4 dish for detecting birds, weather, detached aircraft parts, aircraft with broken-or-otherwise-nonfunctioning transponders, and aircraft without transponders [such as most balloons and gliders], and as a backup in case the aforementioned receiver blew up/contracted malware/got stolen by space aliens).  So why do, or, at least, did, aircraft transponders have to be interrogated by a radar or TCAS before they spill the peanuts?5

1: Which, in turn, enables controllers (for instance) to stack multiple aircraft at different altitudes in close horizontal proximity to one another without risking a mid-air collision (whereas most primary radars can’t determine the altitudes of their targets - since they can measure the azimuth and slant distance of a target, but not its elevation angle - and, thus, can’t be used for vertical separation of targets), to warn aircraft if they sink dangerously low (same reason), to immediately identify new targets appearing on their screens, and to associate said targets with radio transmissions from said aircraft without having to ask the transmitter to make a 360º turn for identification purposes.
2: I’m sure there are a lot of other things transponders are useful for as well, but that I’ve forgotten to include.
3: For instance, this means that an aircraft has to have an operational transponder in order for its TCAS to work - it can’t just sniff out transponder signals sent by nearby aircraft in response to interrogation by other radars and/or TCASses.
4: Radars that detect targets by physically bouncing radio waves off them and listening for the echoes.
5: Like spilling the beans, except that aircraft serve (and spill) peanuts instead.

This podcast covers the history and development of SSR by one of the engineers that worked on the Mode S system, you wont get a better primary source. It likely has what you are looking for and is well worth a listen.

"Why do (or did, until very recently) aircraft transponders wait to be interrogated": Transponder is a short for transceiver/responder, it was designed to respond only. The name is now confusing: Mode S added the possibility to broadcast unsolicited messages (squitters), and this function is likely the only one to survive in a few years. That said, good question.

The Secondary Surveillance Radar system provides range in a method similar to primary radar: by measuring the time between the transmission of the interrogation signal and reception of the reply. The range is proportional to the time difference, minus a constant that allows for the aircraft transponder to perform processing.
This would not work if transponders replied without a interrogation.
Azimuth is traditionally found by observing the direction of the SSR antenna the moment this occurs, though some modern systems utilize the time delay between multiple receiver locations (multilateration).

I don’t get why most (or, until very recently, all) transponders don’t broadcast unbidden

GNSS systems have only been commercially available relatively recently (compared to the timeline of aviation). Also, GPS SA (Selective Availability) was turned off in May 2000 to make available the required accuracy for civilian aviation. ADS-B relies on the aircraft actually knowing where it is.
Basic Mode A/C transponders did not require the aircraft to know where it was. The SSR would determine azimuth, and the Mode A / C replies would provide identity and pressure altitude.
Equipment fitted in certified aircraft changes very slowly. There are still aircraft flying today that were built well before GPS existed. Retrofitting new navigation equipment to an aircraft is expensive.

To the point of this answer, if I remember correctly, the newest aircraft I've personally flown was built in 1980 and the oldest some time in the 1960s. Every aircraft I've flown is older than I am.

The main purpose of SSR is to provide information to the specific station requesting it. Radar antennas are directional when broadcasting and receiving the signals. When the SSR system interrogates the transponder it means the antenna is pointing at it, and so a signal can be received. If the transponder responded when the antenna was pointing away there would be nothing to receive it and the information would be lost.

In addition to the other answers: by waiting for interrogation, you make sure transponders don't transmit simultaneously. This is the big problem with all radio systems: when two transmitters transmit at the same time on the same frequency, both transmissions are unintelligible.

That's not the reason. If two aircraft are at the same distance and (rough) direction from a radar site, they still transmit at the same time.

@RainerP. No. They won't. All radios operate at 1090MHz, they will talk over each other and interfere it's basic physics.

@Sam You misunderstand Rainer's point.  If two aircraft are the same distance and direction they will both hear the interogation and both respond.  The system has to be able to cope with this (because two aircraft in the same place is exactly when you do not want the system to fail).  Given the system can cope with this, rather weakens the argument that challenge-response is to prevent interference.

@MartinBonner: SSR Mode S solves that, by letting the base station specify exactly which aircraft it wants a reply from. And mode S rather than mode A/C is to prevent interference (though not only this kind), which makes this answer valid for a question that is almost but not quite the one that was asked.

@MartinBonner. No. They won't respond at the same time. If they did the system would fail it's literally a law of physics. A response takes a few uS to occur for all practical purposes no two transponders will respond at exactly the same time.

@Sam - You are correct that for all practical purposes no two transponders will respond at exactly the same time, put this is also true for unsolicited broadcasts. This is what Martin and I were pointing out.

I'm not sure about commercial aviation, but in the military there are two antennas involved with IFF - an omni antenna and a directional antenna. The directional antenna is generally what the aircraft respond to. It's unlikely that two aircraft will be at the same bearing at the same distance for very long, I think... The reply would likely be picked up during the next sweep if it was missed or garbled. The response, by the way, are a set of pulses, which are either present or not. There is nothing modulated onto the signal.

Why do aircraft transponders wait to be interrogated before broadcasting beacon signals?

To measure the distance between interrogator and target, similar to how DME works.

I don’t get why most (or, until very recently, all) transponders don’t broadcast unbidden; it’s obviously feasible

It was infeasible in the pre-GPS days, because aircraft didn't know their own position. Even today, the reliance on GPS is a single point of failure and if it is jammed or shut down, aircraft can no longer announce their own position unsolicited. They have to revert to direct distance measurements amongst each other, which requires a challenge-response style of communication.

Great question (with a nice follow-on narrative). Also, great answers! I will add something else I have not read here:
Why not transmit unbidden?
Transponders trace their origins back to the beginining of military Identify Friend or Foe (IFF) technology. In this context, transmitting unbidden is like painting a target upon yourself. Even responding to an interrogation carries risks of an enemy triangulating your position. Transponder equipment in both the vehicle and ground both evolved with this assumption in mind, and certain optimizations were made with certain other trade-offs.

Also note that broadcasting all the time takes a lot more energy than sending a directional signal once in a while.  And if the aircraft (rather than a ground station) does it, that energy adds to the takeoff weight.  I'm not sure how much it matters, but I wouldn't discount it, particularly for relatively small aircraft.


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Would throttle steering of a forward-swept-winged aircraft be possible?
Fortunately (or perhaps unfortunately, given the number of crashes that had to occur for us to figure it out), the use of throttle manipulation to control an airliner with disabled primary flight controls (usually due to a total hydraulic failure) is fairly well established (at least in theory): symmetrical throttle advance to pitch up, symmetrical throttle chop to pitch down, advance left throttle(s) and chop right throttle(s) to yaw and roll right, advance right throttle(s) and chop left throttle(s) to yaw and roll left.1  Pitch control is fairly straightforward (a throttle increase causes an increase in airspeed, which causes the aircraft to pitch up,2 while a throttle chop causes a decrease in airspeed, which, assuming that you are not excessively close to stalling,3 causes the aircraft to pitch down).  The remaining two attitude components, yaw and roll, cannot be controlled separately from each other in the air (because the rudder, which is used to deliberately uncoordinate a turn, is a primary flight control surface, and, thus, is inoperative during this discussion), but this is not a great hindrance, as they generally do not need to be controlled separately in the air unless you’re doing aerobatics (or unless... well, see below).  The aircraft will generally tend to maintain straight flight, unless you happen to also have a failure of a non-centerline engine while your primary flight controls are out fishing (in which case you are both very, very unlucky and very, very screwed).4  Advancing the throttle(s) on one side and chopping the throttle(s) on the other side will yaw the aircraft towards the spooled-down engine(s), which will (as all aircraft producing net positive aerodynamic lift have positive yaw-roll coupling)5 roll the aircraft towards the spooled-down engines; reequalising the throttles will stop the yaw, but (as most large commercial airliners have rearward-swept wings, and, thus, positive slip-roll coupling)6 the aircraft will continue to roll towards the recently-spooled-down engine(s) (even as its natural weathervane stability causes it to yaw slightly back away from said engine(s)) until the aircraft is in a coordinated turn.
In contrast, an aircraft with forward-swept wings will have negative slip-roll coupling, meaning that, although it will still, initially, roll in the desired direction, as soon as the aircraft’s yaw rate decreases below a certain threshold value, it will immediately start to roll in the opposite direction, and will continue to do so as long as the aircraft has a significant sideslip angle.  Unfortunately, this natural rolling tendency takes the aircraft further and further away from a coordinated turn, continuously increasing the aircraft’s sideslip angle and worsening the problem.  As roll and yaw cannot be independently controlled using the engines alone,7 this presents somewhat of a problem for throttle steering on aircraft with forward-swept wings.
I can think of two potential ways in which throttle steering of a forward-swept-winged aircraft could be successfully accomplished:
Method 1: Yaw in the wrong direction to roll in the right direction

Briefly advance the throttle(s) on the outside of the intended turn as far forward as possible, and chop the throttle(s) on the inside of the intended turn to the minimum approach setting.  (Not all the way to flight idle - the engine(s) take much too long to spool up from there!)8
As the aircraft is rolling in the desired direction, equalise the throttles, and then advance the throttle(s) on the inside of the intended turn, but only slightly more than those on the outside of the turn (in order to keep the aircraft’s yaw rate below the threshold value where the opposite rolling moments from the aircraft’s yaw-roll coupling and slip-roll coupling are equal).
Once the aircraft is yawed slightly to the outside of the turn, retard the inside throttle(s) just enough to null the aircraft’s yaw rate and hold it yawed slightly to the outside of the turn.  (The inside throttle(s) should still be very slightly further forward than the outside throttle(s), in order to cancel out the yawing moment produced by the aircraft’s weathervane stability.)  The aircraft’s negative slip-roll coupling will continue to roll it slowly in the desired direction as the aircraft is held in a slight sideslip.
As the aircraft’s roll angle approaches the desired value, equalise the throttles and let the aircraft’s weathervane stability yaw it back into a coordinated turn.  (Some increase in roll rate, courtesy of yaw-roll coupling, will occur as the aircraft weathervanes back in the desired direction.)

Method 2: Yaw fast and hard, but don’t stay yawed

Slam the throttle(s) on the outside of the intended turn forward, and chop the throttle(s) on the inside of the intended turn.
Once the aircraft is rolled considerably beyond the desired angle, slam the throttle(s) on the inside of the intended turn forward, and chop the throttle(s) on the outside of the intended turn, in order to null out the aircraft’s sideslip angle before the aircraft’s slip-roll coupling rolls it too far in the wrong direction.  (The aircraft will still roll considerably in the wrong direction, courtesy of both the aforementioned slip-roll coupling and the yaw-roll coupling as the aircraft yaws back towards the outside of the turn, which is why we deliberately overshot the desired roll angle by a considerable amount.  The saving grace here is the aircraft’s angular momentum, which keeps it initially rolling in the right direction even as the two couplings work to roll it in the wrong direction; were the aircraft’s entire mass concentrated in a single point at its centre of mass, the adverse yaw-roll coupling from nulling out the sideslip would exactly cancel out the proverse yaw-roll coupling from initially yawing into the turn, resulting - when you factor in the negative slip-roll coupling as well - in the aircraft ending up rolled in the wrong direction.
As the aircraft’s roll angle reaches the desired value, equalise the throttles.

Would either of these methods work, and are there any other possible throttle-steering methods for an aircraft with forward-swept wings?  Or are forward-swept-winged aircraft uncontrollable in the lateral-directional axes using throttles alone?

1: Aircraft with neutral or negative static stability (such as a B-2 or an F-117) are impossible to control using throttles alone, as the engines cannot spool up or down rapidly enough to provide the constant control forces needed to keep the aircraft from tumbling like a leaf, which is (at least part of) why all aircraft with neutral or negative static stability are military combat aircraft with a rapid assisted egress mechanism for each occupant.
2: Aircraft with engines mounted high on the tail (such as a DC-9 or a Learjet) have the complication that a throttle increase causes an initial pitch-down moment (due to torque from their engine placement) before the aircraft pitches back up due to increased airspeed, and vice versa, but almost all large aircraft, and even most newer medium-to-small ones as well, have underwing engines, which produce a helpful initial pitching moment in the desired direction even before the airspeed has time to increase much.
3: If the aircraft’s speed is low enough for a throttle chop to stall the aircraft, then a) you’re screwed, and b) the aircraft will probably pitch down anyways, but 1) will do so much more violently than if you hadn’t stalled the thing, 2) will roll off to a very large bank angle in the process, possibly even becoming inverted (like I said, you’re screwed), and c) depending on the particular stall characteristics of the aircraft in question, and the trim setting the horizontal stabiliser was at when primary controls were lost, may actually pitch up instead, possibly all the way into a regime that is usually unrecoverable even with fully-functional primary flight controls, never mind without them (did I mention you’re screwed?).
4: A possible exception might be on an aircraft with two or more engines on each side, such as a 747 or A340 (2 engines on each wing) or an An-225 (3 engines on each wing), or an aircraft with one or more centreline engines in addition to the non-centreline engines, such as a DC-10 or L-1011 (one engine on each wing, plus one in the tail), where an asymmetric engine failure with primary flight controls disabled could be compensated for by shutting down the corresponding engine on the other side, but this would greatly degrade thrust capability (especially if the aircraft is near maximum weight), potentially resulting in an immediate or near-immediate off-airport forced landing.
5: The tendency for an aircraft that is yawing in one direction to roll into the yaw, because the outside wing is travelling faster (and, thus, producing more lift) than the inside wing.
6: The tendency for an aircraft with rearward-swept wings and a non-zero sideslip angle to roll towards the direction that the aircraft’s nose is pointing, because of various disputed effects which I will not go into here.
7: Unless you’re in a multiengine aircraft with thrust-vectoring capability, in which case the engines are themselves primary flight controls, and flying with disabled control surfaces should be little more difficult than normal flight.
8: The purpose of this step is to establish a nonzero roll angle in the right direction, so that the aircraft doesn’t end up rolled in the wrong direction - and, thus, turning in the wrong direction - during the subsequent steps.

Whoever's doing the drive-by downvoting, cut it out.  If there's a problem with the question, flag it, or at least leave a comment explaining what's wrong, rather than doing the electronic equivalent of throwing eggs at someone's head.

No idea why this was down voted, seems like a well thought out and interesting post.

No downvotes here, and it is well though thought out and interesting to the right person, but it's more of an article with a question kinda worked into it and a response would require almost as much time and effort as Sean put into writing it.  Myself I'll kinda skim through it and think it's just too much work to spend time on, and I think a lot of the other regulars on here have a similar reaction.


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Why are accident rates higher on smaller aircraft?
This question was raised as part of this discussion.
Why are accident rates higher on smaller aircraft?
It seems the safety record of military, private and small commuter planes is much less safe than that of large commercial operations and I was wondering what factors cause this?

This seems a bit broad to me as military, private, business, and airline operations are very different, as are the types of small planes they fly.

@Cloud have you considered therapy for your phobia about flying? It seems to be causing you much unhappiness and it doesn't need to.

@zeta-band Hi, thanks for the suggestion. What type of therapy? I have thought about doing a fear of flying course through an airline if that might help

@Cloud The Mayo Clinic has a page on general therapy for phobias. You will have to find a resource in your location that can help with with specific treatment.

The amount of resources that go into commercial aviation are really amazing -- the amount of time, talent, money, and effort that have gone into making the airlines the safest mode of travel known to recorded history is really extraordinary, and the results reflect that.
Design
Aircraft are expensive, but a part of that expense is the extreme care that has been taken to make them highly reliable, with redundant systems and lots of advance warning systems when something is nearing the point of failure.
Fifty years ago, aircraft were less reliable; the engineers have incorporated the lessons learned.  And, considering how much money an airliner make, airlines are generally willing to pay absolutely top dollar for the very safest design possible.
Small aircraft have also benefited from this learning process, but as a matter of economics, they don't get quite as much redundancy or refinement.  While 99.999% might be "good enough" for the general aviation, the airlines can afford the (high) costs of adding more 9's onto the end of that number.
Maintenance
Again, the airlines can afford a maintenance process and inspection regime that would raise the cost of flying a light aircraft significantly.
Mechanics are trained to uniform standards and work in a carefully monitored environment where parts are exactly tracked and the aircraft have an incredibly detailed history of all that's been reported and fixed over their lifespan.
Manufacturers like Boeing and Airbus can see millions of hours of data and spot trends that are developing to head off incipient problems before they become widespread. This, combined with the way that the aircraft are engineered, makes things really, really reliable.
General aviation maintenance is good -- I'm not bashing that -- but airline maintenance, especially at the major airlines, is amazing.  That's not free, but the results are there.
Pilot experience and training
Light aircraft are often flown single-pilot, by a pilot who probably has under 2000 hours, and who may have flown 200 hours in the past year.
On the other hand, airline pilots are typically hired with at least 1000 to 2000 flight hours, often more, and a captain at a major airline may well have 10,000 to 20,000 hours.  Added to that, the crew has probably flown between 400 to 800 hours in the last year, as well as getting multiple days of training -- both ground school and simulator -- as well as at least one if not two checkrides.
Flying is their profession, not a hobby, and they spend time continuously studying the aircraft, its systems and checklists, the environment, and the regulations.  And, they're trained to work as a crew -- if one pilot is about to make a mistake, the other pilot is there to catch it and keep things on track. Not everybody flying light aircraft has these resources.
All of this is possible because, while it is all expensive, airlines can afford it.
And the records speak for themselves -- one fatality in a commercial U.S. aircraft over the last several years -- which includes many millions of flights.  I don't think any other human activity -- including sleeping in your own bed at night -- can claim a similar safety record.
The relevant point isn't that light aircraft flying is "dangerous" compared to commercial aviation; it's plenty safe by normal comparisons.  It's just that airline flying is so incredibly safe, any other activity will look more risky in comparison.

Excellent answer, thanks.

@PhotoScientist  If we all live to 90 years old, having slept 8 hours per night, and then one passes away peacefully in the middle of the night, that is about 1 death per 262,000 person-hours spent in bed. One million flights is probably over one hundred million passenger-hours, so ... yeah.  Some may joke about CRM, but after 2+ decades of studying & using it in crew aircraft, I will say quite confidently that it works well.

"the crew has probably flown between 400 to 800 hours in the last year" Are you sure it'd be that low? That's only a few hours per day, tops, on average. Spend five hours a day actually moving the aircraft from A to B (might be reasonable for a regional airline with lots of short hops) four days a week, and that's already upwards of a thousand hours per year. Even if we factor in things like vacations, sick time and whatnot on top of those three days a week off, it seems like around 800 hours per year would be a low, rather than a high, estimate for just about any commercial pilot.

...the amount of time, talent, money, and effort that have gone into making the airlines the safest mode of travel known to recorded history is really extraordinary -- Not to belittle the point, but it's a bit less extraordinary, IMO, if you consider that humans can (a) walk and (b) swim without any third-party aids. So if your car or boat breaks down, you at least aren't guaranteed to be DOA. Stands to reason then that we'd be at least a bit more worried about the one mode of transportation where there's no natural fallback ;-)

@tonysdg I would venture a guess that flying across the US is significantly safer than walking that same distance, and similarly, that hopping a flight from England to France is significantly safer than trying to swim the channel. And I'm not even factoring in the time; just "will you reach your destination alive."

@yshavit: I heartily agree with you -- I'm merely pointing out that the simple act of trying either of those doesn't immediately guarantee a terrifying death (you can, in theory at least, do both).

@tonysdg 98% of passengers survive a airplane malfunction- so even if the plane goes wrong, you’re almost certainly going to survive.

@PhotoScientist: Haha alright, I admit defeat :) With my sister being an aerospace engineer, I really should know better than to make jokes with aviation enthusiasts ;-)

“Flying is their profession, not a hobby” maybe this also makes them fly more carefully and not for sightseeing or fun?

@RalphJ I'm sure there are 90 years old  who have died on planes from non-aviation causes, and those don't get included in your "one person" stat that you're comparing to deaths while sleeping in your bed. Granted there are still things like carbon monoxide poisoning, fires, bedroom falling into a sinkhole, a drunk driving through your bedroom, your spouse going bonkers and murdering you, etc, so I believe your statement is likely accurate.

Any thoughts on amending this answer in light of more recent revelations about Boeing?

@user541686 No. Even given the fairly disgusting revelations about goings on there, the underlying point remains, unaffected. Even when the Boeing failures produced the depressurization event, the other layers of safety measures (and a healthy dose of luck - which can be present in any human activity) led to a safe recovery of the aircraft with no loss of life.

@RalphJ: ah I see. Though FWIW I was thinking partly of this.

Another factor: commercial airliners tend to fly at high altitudes, over most bad weather and conditions of poor visibility for most of their flight time. Light planes are typically unpressurized, with a ceiling of 12,500 feet (up to 15k feet for short periods of time), which puts them in the conditions of bad weather or poor visibility, not only during takeoff and landing, but for most of their flight time.
The majority of light plane crashes are weather and visibility related... typically a VFR pilot flying into IFR conditions, becoming disoriented due to poor visibility, and crashing... such as the JFK Jr crash.
Commercial flights don't tend to have this happen, partially because the pilots are trained in IFR flying so they're less prone to spatial disorientation when they can't see the horizon, partially because they have the experience and the equipment/information to detect and avoid really bad weather, and partially because they're usually flying over most bad weather and conditions of poor visibility, not in them.

Large commercial flights, two engines, two pilots. More eyes and hands to handle loss of an engine. Very high recurrent training standards mandated.
Owner flown and other private pilot flights, it's usually attributed to lack of training. Flying into IFR weather without the rating, or practice, or equipment (think icing conditions). Or fuel exhaustion.  Much less training after an initial license, or add on rating (instrument, maybe commercial, maybe other plane types.  For example, mine stopped after the instrument rating, and I only flew my plane, so I just became really proficient in it).
Medium to large Business, they typically have professional pilots flying the plane. Small business might have the owner as pilot and I'd have to see stat's on their accident rate. I bet the rate is pretty low.
Then there's things like helicopter conducting sight seeing tours over the Hudson River in NYC.  I think that was mechanical failure.
Military - I believe that outside of war theaters, the accidents usually occur during training, and they do a lot of it. Fly enough hours, and something is bound to break, or an unrecoverable situation occur, or just plain human error occur.

Don't forget auto pilot. And can't ATC land some planes from the tower?

@Mazura - no, not at all.  ATC is like a traffic cop, but the driver still guides the vehicle.

Small planes (my definition of small, 2-4-6 seats, vs FAA definition, which is anything up to 12,500 lbs) have autopilot as well.  Avionics in small aircraft can be pretty advanced.  Affordable Flight Management Systems (FMS) give us the same capability as the big iron. Only thing missing is the autoland in zero-zero conditions, and capability to land in 50 and 100 foot ceilings. The larger small planes are often flown commercially and may be better equipped for the lower ceiling approaches.  We with IFR ratings have to fly a minimum number of approaches to stay current to able to file IFR.

Simulated terrain views based on GPS position and altitude is also becoming common, mimicking the infrared views found on more expensive planes. Bigger planes may have radar too for better avoidance of weather.

For general aviation, it's mostly the higher probability of accidents caused by bad judgement; flying VFR into IFR, running out of gas, overloaded takeoffs, incompetent handling close to the ground, etc.  Whereas the airline world is highly regimented and operates on clear go-no-go criterea, with backups of backups both system wise and procedurally.  When I was bush flying on floats, the dangers were mostly due to the need to make constant judgement calls on weather and loads etc. It's a world of greys, not black and white and of living by your wits.  Very challenging but loads of fun.
Anyway, filter out all the GA accidents caused by incompetence and poor airmanship, and I believe you start to approach the safety of airline flying.  Because if you are in a Chevy Biscayne of the sky like a Cessna 172, that is halfway well maintained, on a sunny day, full of gas, and you have some minimal level of good skills and judgment, you really really have to work at it to kill yourself.

Why is running out of gas so common? I mean, people don't do it in cars very often so how it happens so often in private flight?

@Cloud: I think it happens more than you think in cars. It's just that the consequences aren't as newsworthy as they are with airplanes.

Typically a light plane flies into conditions of poor visibility, such as fog or rain, and runs out of gas trying to find an airport with good enough visibility to land. Unlike airliners, light planes don't have the equipment, nor does the pilot have the training, to use the Instrument Landing System that guides airliners to a landing in bad weather. Also, inexperienced pilots are slow to even detect an emergency situation, let alone declare one to get the help to get down safely.

Folks running out of gas are typically low wing aircraft where a pump is needed to get the fuel up to the engine from one of two, or several, tanks, vs high wing where gravity gets the fuel down.  The wrong tank is selected, and the pilot is not able to get the engine going again in time after the correct tank is selected.  More-than-2 tank aircraft often have to deal with additional means to get the fuel from a wing-tip tank other tank into one of the two main tanks to feed the engine.

Light planes DO have Instrument Landing System equipment. We just may not be able to make it down to 50 feet, or have autolanding, like the big iron boys & girls can. For example, the lowest I can go is 200 feet above runway height, if I'm not out of the clouds by then I'm going around to try again, as conditions do change, or I'm going elsewhere.

@CrossRoads I don't think the answer was meaning to say that light aircraft don't have ILS equipment, but rather than non-IFR-rated pilots flying into IMC is a significant cause of death (which is true.)

line 2 s/IFR/IMC/ but like reirab says, that's an example of a difference in training.  Every jetliner pilot is trained to fly in instrument meterological conditions (clouds etc.; flying in soup is hard). But they'll happily hand you a 1-engine Cessna without it, in fact many private pilots take years to pick up their instrument rating, or never do. This is a recipe for disaster when they meet an errant cloud or scud-run.

All aircraft and pilots must meet certain standards to be deemed fit to fly. For example: all parts used in an aircraft (general, commercial, or military) must have accompanying documentation attesting to their fitness for use in an aircraft - traceability to point of manufacture, inspection, etc.. Aircraft used in commercial transport do require more frequent inspection than general aviation, but that shouldn't make general aviation less safe. Commercial pilots require more frequent medical examinations, require periodic "check rides" and generally end up more closely monitored for proficiency than private pilots. Also, commercial pilots tend to accumulate far more flying hours, so commercial pilots are usually more experienced than private pilots. That said, commercial pilots always start out as private pilots. General aviation aircraft far outnumber commercial aircraft; there are far more general aviation aircraft movements than commercial aircraft. Military aircraft have to operate in hazardous conditions - combat aircraft have to be flown to the edge of their flight envelope to gain a tactical advantage and/or escape a threat; even military transport sometimes have to be operated at their extremes to either get in and out of tight and/or unprepared places or avoid becoming a target. This sort of flying must be practiced regularly so that the pilots get it right when it matters most, so military flying is often riskier than non-military, even in peacetime.
So,
A higher incident rate among general aviation can be attributed to sheer statistics - just more of them around, and also to a lower level of pilot skill, experience, or discipline.
A higher incident rate among military aviation can be attributed to the extremes to which plane and pilot have to be pushed, and the greater likelihood that either/both will from time to time be pushed a little too far.

You have some useful points here, but "more flights inevitably equals a higher accident rate" isn't really accurate. Aviation accident rates are often given per 100,000 flight hours, for example, which allows you to compare rates in commercial vs. GA regardless of the occurrence (the absolute number) of accidents.

@Pondlife Good point. Flight durations probably are longer for commercial flights than general aviation, on average, but most accidents/incidents occur during or around takeoff and landing than during cruise. Since general aviation likely performs more takeoffs and landings per flight hour than commercial, it would be reasonable to expect that takeoff and landing related accidents would be higher per flight hour for general aviation than commercial even if rates per movement were the same.


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What noises are considered worrying on a passenger flight?
As a typical 'nervous flyer', I often find myself asking crew about a noise that they say is completely normal during flights. The thing is, I've flown a lot and still hear new sounds sometimes!
For example on a recent Easyjet Airbus flight, when the aircraft went into full throttle to take off, a loud whirring/buzzing sound started and lasted the whole flight (I was sat on the wing)... still no idea what that was.
So what is a general list of sounds that are to be expected vs a list that tells you that you are all but doomed :/
Let's keep this to an Airbus Easyjet might use to keep it a short(er) list.

considered by whom?

No noise in a jet airliner is in general a bad omen

@user3528438 well... obviously someone with knowledge about aircraft, i.e. people on this site presumably.

That sound you heard was probably just the engine fans spinning and breaking the sound barrier, as normal. A320 engines are IMO the worst for noise if you are seated next to them, at other ends of the aircraft it's more tolerable. But trust me, as annoying as the buzz might be, your flight would be a lot worse if it went silent.

@Ben Thanks very much, really useful to know :)

The only noise (other than a clear and obvious explosion) that gets my complete and immediate attention is "This is the captain..."

What? Not the flight attendant telling you "please open that emergency exit door"?

Is that what they are saying? When I sat at the exit, the flight attendant told me that she would yell "Evacuate, evacuate, evacuate!" and that would be my cue. Although maybe on British Airways it is "Dear Sir, may I be so rude as to emplore you to open the emergency exit door at your earliest convenience, if you don't mind?"

"BRACE BRACE" is usually a dead giveaway! (No pun intended)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
What is the ATC protocol for hijackings?
If a commercial aircraft is successfully hijacked, by a competent pilot / pilots, and they make contact with ATC for regular requests (i.e. weather updates, flight path information or clearing air traffic), will ATC still aid the (new) pilots, or do they have some other procedure, like trying to persuade them to hand control back to the original pilots?
I'm just wondering if there is a formal procedure for such an event, as I'm guessing it's rather unlikely that they would contact ATC like that. But always possible, of course.

I'm sure there are protocols for who they notify, but procedures will vary widely between countries. As for giving assistance, if the hijackers intend to land the airplane it's in the interests of everyone that ATC helps them. Knowing the intentions would be tricky of course.

Example: https://www.theguardian.com/world/2014/feb/17/copilot-arrested-hijacking-ethiopian-plane

@Ben Very interesting but I wonder if he actually spoke to ATC to land? Or just went for an empty runway...

@Pondlife Will they release it if someone emails them? Or maybe someone working for FAA on this site can obtain the procedures...

@Cloud I have no idea, but I think it's very unlikely. Why would the government share (presumably) classified security protocols with anyone who just asks?

@Pondlife Hmm... ok, I'll give it 24 hours and if nothing, maybe close the question. Thanks.

@Cloud They're not publicly available. We are the public. Therefore, they are not available to us.

@DavidRicherby Sure, but the question actually had a suitable accepted answer, not sure I see the benefit in closing the question after the fact.

In the US, the ATC protocol for hijackings is classified for reasons of national security.

10-2-6 Hijacked aircraft
Hijack attempts or actual events are a matter of
  national security and require special handling. Policy
  and procedures for hijack situations are detailed in
  FAAO JO 7610.4, Special Operations.‡ FAAO
  JO 7610.4 describes reporting requirements, air crew
  procedures, air traffic procedures and escort or
  interceptor procedures for hijack situations

Air Traffic Organization Policy, FAA, 2015-12-10.
‡This document's content can only be accessed from within the FAA network.

I thought maybe some ATCs would be active on this site that could reveal the info... thanks though :)

As valuable as internet points are, not sure they’re worth risking your job, country, and freedom for.

According to ICAO doc 4444 ATC will treat the hijacked aircraft with extra care - since the aircraft is considered to be in a state of emergency. Extra separation will be provided between the hijacked aircraft and other aircraft.

15.1.3.3 Whenever unlawful interference with an aircraft is known or suspected or a bomb threat warning has been received, ATS units shall promptly attend to requests by, or to anticipated needs of, the aircraft, including requests for relevant information relating to air navigation facilities, procedures and services along the route of flight and at any aerodrome of intended landing, and shall take such action as is necessary to expedite the conduct of all phases of the flight.

This does not mean that the authorities will not take some other actions - but what they will do is classified.


text:
Is it possible to fly 'in neutral'?
Sometimes, when I am driving, I knock the car 'out of gear' or set the stick to the neutral position, to save fuel. This is most easily done when cruising down a hill or when you have some good speed and are approaching a stopping point, i.e an intersection.
Is there a flying equivalent for pilots? I'm wondering if during descent, or even a landing, fuel could (safely) be saved by reducing thrust to zero and gliding.

Not related to aviation, but putting your car in neutral does not generally save fuel. Your engine continuously needs fuel to keep idling in neutral, while it would not need any fuel if it is driven by the wheels.

In a glider, the moment you release from the launch you are flying "in neutral" ;)

Driving with neutral down the hill is a good way to change mode from driving to flying.

FYI- a significant majority of cars built in the last 10 years or so will cut fuel flow to one or more cylinders when you lift off the throttle, some will stop all fuel flow when you lift off. i.e., just coasting will do the trick, you don't have to be in neutral. Of course, you'll coast further without the compression drag of the engine...

To actually reduce engine thrust to zero would require in-flight shutdown of all engines. As already discussed, this isn't done for a variety of reasons; one such reason is the use of bleed air, and another is that starting the engines is a multi-step process that can take some time even without the complexities of starting an engine that is windmilling rather than at a standstill, and a third is that engines provide more than thrust (such as hydraulic pressure or electricity for non-critical but still useful systems, including additional radios). Shutting down all engines in flight is something you really don't want to do, because doing so deprives the pilot of options; for example, it makes a go-around or even just handling an unexpected gust of wind far more involved than it needs to be.
What is often done, however, is to reduce thrust to idle. Idle thrust does not mean zero thrust; idle thrust generally means some low amount of thrust above the minimum required to keep the engine safely running (which itself is typically non-zero). Because the engines are still running, it's a relatively simple process to increase thrust if needed, which means that unexpected events during the descent can be dealt with much more rapidly and safely.
There are other ways to descend. The pilot could simply point the nose towards the ground and leave the engines where they are (assuming no autothrottle or similar system), but that will cause speed to increase. In light motor aircraft, it's probably pretty common to compensate for this by simply reducing engine thrust along with pitching the aircraft down, unless you actually want to descend under power.
Another option, which is probably more common on large aircraft, is to deploy high-drag devices such as spoilers or air brakes without a corresponding increase in engine thrust.
Remember that the aircraft can be treated as an energy system with fuel burn (controlled by the thrust levers) providing energy input, lift helping keep the aircraft in the air, and gravity and drag costing energy (in different directions; typically downward and forward, respectively). If you increase drag, for example by deploying high-drag devices, then basically one of two things will happen: (1) the drag of the aircraft increases (duh) which means that if you were previously in an equilibrium, you are now "spending" more energy than you have available, causing either a descent, a reduction of airspeed, or both; or (2) you will need to increase thrust to compensate for the increased drag to maintain speed and altitude. (#2, by the way, is why the landing gear is retracted early during the climb-out; doing so reduces drag, leaving you with more power for climb.)
An effect of #1 is that you can control the pitch of the aircraft to choose how much the speed changes, and how much the altitude changes. (Airspeed and vertical speed, respectively.) The pilot (or autopilot) can simply pitch the aircraft to maintain a desired airspeed and let the vertical speed become what it may, or they can target a vertical speed by pitching for that and simply monitoring the airspeed to make sure they aren't overstressing the airframe on the high side, or approach the stall speed for the current configuration on the low side.
All in all, airplane pilots have lots more options than car drivers (and the above doesn't try to provide an exhaustive list), but something exactly resembling "neutral" in a car isn't one of them.

Reducing thrust is the normal way to descend, though given that the prop is bolted to the crankshaft, you don't really have a neutral*.  It's exactly the same as taking your foot off the gas pedal in a car.  Depending on conditions, you may or may not want to go all the way to idle until you're actually on the runway, thought.
You can use other techniques to increase the rate of descent, such as slipping or deploying spoilers if your plane has them (most common on sailplanes), which would be equivalent to using the brakes on your car.
*As others have alluded to, shifting to neutral isn't the most fuel-efficient way to decelerate in a modern car.  Most if not all have what's called Deceleration Fuel Cutoff (DFCO), which shuts off fuel completely when decelerating in gear.  In neutral, the engine uses a small amount of fuel to idle.  Given that most airplane engines are '50s tech, this doesn't really apply to them, though.

"most airplane engines are '50s tech" In GA, maybe. Definitely not in commercial aviation. Even propeller aircraft in commercial aviation have their engines upgraded more often than that. (In fact, I'd almost challenge you to point to any single commercial carrier, passenger or cargo, that still flies for commercial purposes any airplane originally built in the 1950s, let alone one that hasn't had its engines replaced since then.)

@Michael Kjörling: Once again, we get hit by the problems of mixing GA and commercial aviation.  The OP's question is about saving fuel: why would s/he be interested in doing that unless they're flying their own plane?   (Or one that they rent.)  I doubt whether many of us here own jets, or even commercial propellor airplanes :-)  For the minority who are or have been paid to fly them, I'd think that basic fuel management questions would be covered in commercial/ATP level training :-)

@MichaelKjörling haha, Michael, you really don't like me :p

Autorotate on a helicopter is like neutral.

Is there a flying equivalent for pilots? I'm wondering if during descent, or even a landing, fuel could (safely) be saved by reducing thrust to zero and gliding.

Reducing power is indeed a means of initiating a descent, and a pilot may reduce the thrust to idle if they choose to.  You will notice this on most commercial flights; as they are nearing their destination the engines will go quieter (as the thrust is reduced) and the aircraft will descend from their cruise altitude.
However, most pilots will not routinely do a glide approach and landing.  Most commercial airports will have a specific angle of approach (rate of descent between a given point and the runway) that inbound aircraft will need to use.  Power is used and adjusted to maintain the correct rate of descent - if the aircraft is descending too quickly, power is added, if not quickly enough then power is reduced (to idle if necessary).  Again, you may notice this on approach in a commercial flight, particularly on a turbulent day - you will hear the engines spool up and down as the pilot adjusts the rate of descent.
There are exceptions.  Glider pilots will naturally always do a glide approach as they have no engine.  They control their rate of descent through the use of airbrakes or spoilers, which increase drag (air resistance), so they must descend more quickly to keep flying at the same airspeed.  Some other light aircraft pilots may also prefer a glide descent and landing where possible.
Pilots of all types will often practice glide approach and landings so they are ready to handle an engine failure. Famous examples of engine-out landings include the Gimli Glider and more recently the landing in the Hudson.

Jet aircraft only have a thrust lever to set the power level. Even at idle most engines will still be producing some forward thrust. If shut down, the engine will produce drag.
Fixed-pitch propellers run at the same speed as the engine, so as with jet engines you can only adjust the engine throttle, and it will either be producing thrust or causing drag. Small aircraft use this because it is a simple setup.
Constant-speed propellers are able to adjust the pitch of the propeller blades, called feathering. This would be closest to having "neutral" as in a car, as you can adjust the prop speed (which follows engine speed and affects thrust) independently of the engine power. However, these aircraft typically have limited ranges of propeller RPM where they are intended to operate. These propellers can also use their pitch change to provide reverse thrust to slow the airplane down, primarily on landing. Some can do this in the air, which is more like downshifting in a car. When an engine fails, the propeller is feathered so that it provides the least amount of drag.

Note that constant speed props run at the speed of the engine, too.  They change the amount of thrust by changing the blade angle: https://en.wikipedia.org/wiki/Constant-speed_propeller    Reversing doesn't change the direction of rotation, but the angle of the propellor blades.

@jamesqf, actually constant-speed propeller engines change the amount of thrust by changing the fuel flow like any other engine and the blade angle changes to maintain the angular speed (power is angular speed times torque; fuel flow controls power, blade angle controls the ratio between torque and rpm).

@Jan Hudec: That depends on how you look at it.  I think it's equally valid to say that changing the blade angle changes the amount of thrust, which requires more fuel to maintain the same RPM.

@jamesqf, you could, but mine describes how the controls actually behave—an engine with constant-speed propeller has a power lever and a RPM lever and the pitch is adjusted by governor as a result of those two settings. Your description does match helicopters though where collective controls the pitch directly, immediately adjusting lift and trading some of the kinetic energy of the rotor, while the throttle is adjusted by pilot or governor to keep the rpm within limit.

If the car is in neutral and you don't want to slow down, you have to be going down a hill with just the right slope to maintain the speed you are at.  If you do it on level ground, the car will slow down.  Airplanes are the same from a conservation of energy standpoint, but the pilot gets to choose the slope of the hill, as well as the speed.

One of the old-timers at my gliding club told me about a flight he took along the Blue Ridge Mountains, where the controller gave him a vector that was a few miles away from some strong mountain wave lift.  He kept veering into the lift to increase his ground speed, and the controller would remind him that he was off-course.  After a few iterations of this, the controller gave up and granted him an amended vector where he could fly in the lift at significantly increased ground speed and reduced fuel burn.
IIRC, his scheduled 4-hour flight was reduced to slightly more than 3 hours.

Makes me wonder why the pilot didn't just ask for an amended vector...


text:
How much do '1,500 total hours with 500 multi crew hours' cost in Europe?
This company offer a 'fast-track' modular course which, in their words:

Our speciality is the training of pilots with no flying experience to become Fastrack airline ready pilots by means of continuous Modular training. If this course is commenced on a full time basis it is possible to complete in under 12 months however the majority of students will take between 12 – 18 months to graduate. This will provide the cadet with a ‘frozen’ European Aviation and Safety Agency (EASA) Airline Transport Pilot Licence (fATPL). The Licence will remain ‘frozen’ until 1,500hrs of Total time and 500hrs of Multi Crew time have been achieved.

They also add:

100% of Aeros Fastrack graduates have been placed with major airlines across Europe over the past two years.

All for the relatively low cost of around 62,000 Euros.
My question is about the last part of that, regarding hours. How much time (months/years) and how much money would it cost to achieve the 1,500 total hours with 500 multi crew hours after completion of the fast-track?
Several aviation forums suggest this is a much better deal than the airline provided schemes, where they normally charge around double this in order to actual turn a profit on training.

There are 8760 hours in a year, if you flew 6 hours per day it would take roughly 250 days to get 1500 hours. I know quite a few people who did this by taking an instructor job. I'm curious about the multi-crew though, in the US, it is "multi-engine", not multi-crew.

@RonBeyer I guess I wanted to know how many hours you get from the course, so as to calculate remaining hours and then get an idea of (realistically) how long it would take you to log said hours.

I'm fairly certain that the course you show only takes you up through the CPL and then the ATP practical (ground course), which would be a minimum of 200 hours, which jives with the information provided (a "target" of 185 hours and then 15 hours of CPL instruction) in the link you provide. So at the end of this course you still have to make up 1300 hours.

You get to the 1500 hours by working in a flying job once you have your comm/group 1 IFR, which is where the 62k gets you.  Even if you wanted to spend a decade renting airplanes to get the time in, for the 500 multi-crew part you have no choice but to find a flying job since there is no other way to get those hours unless you are rich enough to afford your own multi-crew airplane.
The course gets you to a minimum employable level of flying hours (maybe 250-300 or so - hard to see 60k getting your any farther than that) and with the EASA ATPLs written, which allows you to copilot multi-crew aircraft as a greenhorn 300 hr copilot (normally you get a "multi-crew" license, which is a trimmed down version of the ATPL for low time pilots to serve on 2 pilot a/c) without having to write the exams again when you get the time in (that's the "frozen" part).  Most jurisdictions will "freeze" your exam validity for 3 years.
The "fast track" bit just means they cram the whole thing into one year.  That would be a pretty intense course, jamming 2-300 hours into 12 months with the ATPL ground school thrown in as well.

What if you can't get the flying job?

Then you're done.  You instruct, hire on as a copilot with a 3rd tier commuter or charter company flying old junk, fly in the bush.  Getting the first job is the hard part, although WAY easier today than 10 or 20 years ago (a commuter company operating piston twins or Beech 1900s will take 300 hour wonders now, when it used to be 1000 hours minimum).  After that, it's just don't screw up and make sure you don't make enemies in the trade.